In order to produce speech sounds that comprise the acoustic signal of human language, a complex set of coordinated muscle movements must be realized. Each speech sound requires that a unique series of movements be performed. For example, the tongue must change shape and/or make contact with various landmarks within the oral cavity, often in a precise sequence of movements with each movement corresponding to at least one ideal pronunciation of a particular speech sound.
Many people, particularly children, experience speech sound disorders in which the speaker may not be able to effect the particular series of movements necessary to produce a particular speech sound. For these individuals, the improper series of tongue movements may result in distorted speech sounds that affect the overall intelligibility of an individual's speech. Some speech sounds (called “phonemes”) in a speaker's native language may not be produced, may not be produced correctly or may not be used correctly. Speech sound disorders are typically classified into articulation disorders (“phonetic disorders”) and phonemic disorders (“phonological disorders”), although some speakers may suffer from a mixed disorder in which both articulation and phonological problems exist (see http://en.wikipedia.org/wiki/Speech_sound_disorder#Articulation_Disorders).
Errors produced by speakers with speech sound disorders may include omissions (certain sounds are not produced, or entire syllables or classes of sounds may be deleted), additions (extra sounds are added to the intended words), distortions (sounds are changed slightly so that the intended sound may be recognized but sound “wrong”, e.g., as in a lisp) and substitutions (one or more sounds are substituted for another, e.g., “wabbit” for “rabbit”). The magnitude of such errors can vary among speakers, and some errors may demonstrate variable magnitude in errors among different sounds. Some speakers may involuntarily demonstrate more than one error during speaking.
Various attempts have been made to diagnose and treat speech sound disorders in a manner that addresses the varying magnitude of speech errors as well as the wide array of possible causes for such errors.
U.S. Pat. No. 4,112,596, for example, is directed to a pseudo palate used for diagnosis and treatment of speech impairments. The disclosed pseudo palate is formed of a thin material sheet shaped to the contour of the patient's palate. An array of electrodes is provided on the lingual surface of the sheet with the electrodes having predetermined spaces therebetween. Conductors attached to the electrodes are embedded in the sheet and grouped together to exit from a posterior portion of the palate for exit from the patient's mouth. With the pseudo palate in place, a small voltage is applied to the patient's body, for example, by securing an electrode to the patient's wrist. The conductors communicate with processing and display equipment that provides visual and/or aural signals corresponding to a position of the tongue when the patient makes, or attempts to make, designated speech sounds.
U.S. Pat. No. 6,974,424 is directed to palatometer and nasometer apparatus. The palatometer includes a flexible printed circuit with electrodes that fits in a patient's mouth. The position and movement of the tongue and lips are indicated on processing and display equipment in communication with the electrodes. The nasometer includes a set of interchangeable sound separator plates to fit patients with different facial curvatures. Microphones are attached to each sound separator plate to measure sound emitted form the nose and mouth for determining the nasality of speech.
U.S. Pat. No. 6,971,993 is directed to a method for providing speech therapy that uses a model representation of a position of contact between a model tongue and mouth during speech. A device is used that includes a sensor plate having sensors for detection of contact with a user's tongue. Representations of contact between the tongue and palate during speech can be viewed and compared with model representations (for example, on a processing and display device having a split screen). The model representations, which may be mimicked for speech enhancement, may be generated by another speaker using a sensor plate or by computer generated representations that have been electronically stored.
U.S. Publication Nos. 2009/0138270 and 2007/0168187 are directed to speech analysis and visualization feedback integrated into speech therapy methods. In U.S. Publication No. 2007/0168187, an audio input of a computing system receives a speech signal that is visually compared with the ideal pronunciation of the speech signal to visualize relative accuracy. In U.S. Publication Nos. 2009/0138270, a sensor plate having a plurality of sensors is disposed against a learner's palate. A set of parameters representing a contact pattern between the learner's tongue and palate during an utterance is ascertained from a speech signal. For each parameter, a deviation is measure is calculated relative to a corresponding set of parameters from an ideal pronunciation of the utterance. An accuracy score is generated from the deviation measure.
U.S. Publication No. 2008/0228239 is directed to systems and methods for sensory substitution and/or enhancement for treatment of multiple conditions that involve the loss or impairment of sensory perception. Some systems may train subjects to correlate tactile information with environmental information to be perceived, thereby improving vestibular function. In one example, tactile stimulation (e.g., electrotactile stimulation of the tongue) is relied upon in applications where deep brain stimulation is used and contemplated for use.
These known methods and devices employ complex visual and verbal cues to indicate correct movement and placement of oral articulators. Speech sounds requiring proper tongue position, shape, and movement are difficult to teach because the required tongue position, shape, and movement take place behind the teeth and are therefore difficult to show to a patient. Consequently, it is difficult for patients to assimilate these types of complex motor patterns when taught with traditional visual and verbal cues. In particular, complex verbal cues used to teach proper tongue shape and movement may be difficult for younger patients to process.
Despite these known methods and devices, a need persisted for improved approaches for the recognition and treatment of different speech pathologies. Applicants addressed this need by providing methods and devices that employ intraoral tactile feedback to train proper tongue positioning corresponding to particular speech sounds (see Applicant's U.S. Pat. No. 8,740,622 B2, the entire disclosure of which is incorporated by reference herein). Applicant's disclosed methods and devices are intuitively used by speakers, therapists and family members (such as parents and other primary caregivers) for use in navigating the speaker's oral cavity and reinforcing proper tongue placement therewithin. Applicants' disclosed methods and devices also promote interchangeability and modularity for creation of multiple speech sounds, and portability for encouragement of use in a variety of environments, thereby leading the speaker to realize beneficial results within a shortened timeframe.
These and additional attributes are provided by methods, devices and systems disclosed herein that provide intraoral biofeedback, both independently and in cooperation with a software platform.